Automated coagualtion testing has been accomplished by apparatus developed in recent years. Thus, apparatus has been devloped for testing plasma samples for prothrombin time, activated partial thromboplastin time, factor assays, and many other tests. Prior art devices have included means for pre-warming components in fluids and have utilized photoelectric systems for measuring coagulation time. In fact, such devices as the COAG-A-MATE single channel clot detection system sold by General Diagnostics Division of the Warner-Lambert Company has been very effective for such measurements. Devices for a similar purpose are manufactured by Medical Laboratory Automation, Inc. as the MLA Electra 620 and 600 Coagulation Timers. These devices have been described in U.S. Pat. Nos. 3,477,822 and 3,540,858. Additionally, many trays have been developed for testing samples photo-optically, which prior art devices are shown in U.S. Pat. Nos. 2,879,141; 3,038,340; 3,041,146; 3,368,872; 3,449,959; 3,469,438; 3,477,821; 3,477,822; 3,480,398; 3,480,399; 3,532,470; 3,540,858; 3,554,704; 3,544,705; 3,574,553; 3,594,129; 3,676,080; 3,690,833; 3,692,487; 3,692,488; 3,704,099; and 3,707,354.
U.S. Pat. No. 3,969,079 relates to an improved photo-optical clot detection apparatus having dual channels to provide simultaneous evaluation of two samples. The circular cuvette remains stationary during the test. Reagent dispensing means is provided at both sample stations.